1. Field of the Invention
The present invention relates in general to transducers, and more particularly to acoustic transducers. The present invention also relates to a transducer capable of radiating acoustic energy over a wide band of frequencies. More particularly, the present invention relates to an acoustic transducer that may be provided with an electro-mechanical feedback system.
2. Background and Discussion
Normally electro-acoustic underwater transducers are operated in the vicinity of the fundamental resonant frequency. Maximum output is obtained at the resonant frequency; however, operation in the vicinity of this frequency limits the bandwidth of the transducer. Wideband performance can be obtained above resonance but the band is often limited by the next overtone resonance. Because of phase shifts, the presence of this overtone resonance generally creates a cancellation between the two resonant frequencies typically resulting in a significant reduction, or notch, in the level of the response, thus limiting the bandwidth.
It is a general object of the present invention to provide a transduction apparatus, which eliminates the reduction in the level of response, attaining a wide bandwidth above the fundamental resonance through in-phase addition in the response between the fundamental and overtone resonant frequencies.
Another object of the present invention is to provide a transduction apparatus which uses the harmonic or overtone resonant frequencies to provide broadband electromechanical coupling.
A further object of the present invention is to provide electro-mechanical feedback control resulting in an improved response under single element and array loading conditions.